1. Field of the Invention
The present invention relates to an LED and, more particularly, to an LED that provides better light-mixing effect by stacking chips.
2. Description of Related Art
A conventional LED utilizes blue light to excite a fluorochrome material to cause the fluorochrome material to emit yellow light, which is mixed with the blue light to generate white light. Alternatively, the conventional LED utilizes a parallel blue chip and yellow chip (shown in FIG. 5 and FIG. 6) to emit the white light. The blue chip 93 and the yellow chip 94 are stuck on the conductive supporting frame 91 of the LED 9 by conductive paste 92, and the electrical power supplied by the conductive frame 91 is used to make the blue chip 93 emit the blue light and the yellow chip 94 to emit yellow light. By controlling the electrical current and voltage, the LED 9 with the characteristic of a single wavelength can make the blue light and yellow light diffuse and mix to provide white light.
However, the LED 9, which has the parallel chip 93 and chip 94, has a problem in mixing the lights, and also has a color fleck problem. The reason is that the distance D between the parallel chip 93 and chip 94 causes the LED to display different colors on two sides of the LED, the blue LED chip 93 side showing blue light and the yellow due to difficulties in processing that the distance D between the chip 93 and the chip 94 cannot be made closer or the chips will be short-circuited and leaking current problems will result, which causes the additional problem of decreasing the yield.
The main objective of the present invention is to solve the aforesaid problems and to provide a stacked, light-mixing LED in which by mixing two lights with different wavelengths in the visible light spectrum area, excited and emitted from a first chip and a second chip, and by controlling electrical current and voltage, the two lights excited from the first chip and the second chip can be mixed into another wavelength of light in the visible light spectrum area, such as the white light, to provide a better symmetric light-mixing effect and avoid a visible color difference.
Another objective of the present invention is to provide a stacked, light-mixing LED without the problem of short circuits and leaking current by stacking the first chip and the second chip.